Recording device



y z 1953 G. F. GARDNER 2 644,738

RECORDING DEVICE Filed March 22, 1951 Inventor:

George F. Gardner;

His Attorney Patented July 7, 1953 RECORDING DEVICE George F. Gardner,Scotia, N. Y., assignor to General Electric Company, a corporation ofNew York Application March 22, 1951, Serial No. 217,007

1 My invention relates to recording devices and more particularly torecording devices in which the recording is made on energy sensitiverecording material by an energized marking member.

In such devices the problem of supplying the proper amount of energy tothe marking member often presents serious trouble. For example, inrecording instruments which use heat sensitive papers and a heatedmarking member or stylus for recording variations in a predeterminedquantity, considerable difficulty is encountered in obtaining thecorrect heat in the stylus for the speed at which the stylus is movingat any given moment. In conventional recorders, the stylus temperaturenecessary to produce a legible record when the stylus is at rest isinsufiicient to produce a clear line when it is moving rapidly.Conversely, if suflicient heat is applied to make a good record when thestylus is moving, the record obtained when the stylus is stationary isbadly blurred and most unsatisfactory. A similar problem is oftenencountered in recording devices which use an electrically sensitiverecorder material that is marked by the passage of an electric currenttherethrough. In certain of these devices,'the electrical signal whichdoes the marking is applied across the recording material between astationary printing bar or plate and a pen stylus. Unfortunately,however, a signal which is strong enough to pierce the paper and make aclear mark at low speeds of the stylus is insuflicient to make a legiblemark at higher speeds of the stylus.

Therefore, a primary object of my invention is to provide new andimproved means for varying the energy input to a recording stylus inresponse to variations in the quantity being measured.

' Another object of my invention is to provide new and improved meansfor varying the temperature of a heated recording stylus in response tovariations in the quantity being recorded.

' In accomplishment of the foregoing objectives, I provide an energycontrol system in which the energy input to the marking member or stylusis controlled by the output of a circuit which includes in serialrelationship a rectifier and an amplifier. To make the output ofthe'circuit responsive to the variation of the quantity being recorded,the rectifier is energized by the same signals which initiate movementof the marking member. The exact manner in which the output of theamplifier is employed depends upon the type recorder in which the systemis to be used.

For a better and'more complete understand- 4 Claims. (Cl. 346-'76) ingof my invention, together with additional objects and advantagesthereof, reference should now be had to the following description andthe accompanying drawing, which is a schematic diagram of a preferredembodiment of my invention.

Referring to the drawing, the signal to be recorded, for example, afluctuating current, is applied to the moving coil I of an indicatingdevice 2 through a pair of supply conductors 3 and 4. In device 2, coilI is pivotally mounted in cooperative relationship With the field polesof a permanent magnet 5 so that variations of the current in coil Iresult in motor action between the coil and magnet 5. A recording arm 6is positioned on coil I and as coil I moves, the recording arm isangularly displaced a corresponding amount. Moving with recording arm 6is a stylus loop I consisting of a heating coil of conducting material,such as Nichrome. More specifically, the stylus loop is disposed to heata marking member or stylus 8, which is mounted on recording arm 6.Heated stylus 8 contacts a moving sheet of heat sensitive recordermaterial 9 to provide a permanent record of the current fluctuations, asindicated by coil I.

The current for heating stylus 8 is supplied to loop I from anessentially constant voltage a1- ternating current source It through apair of supply conductors II and I la. Also included in this powersupply circuit, in serial relationship to loop 8 and source Iii, is awinding I2 of a saturable reactor I3. It is through regulation of thereactance of winding I2 that control of the heating current in loop I isaccomplished. A second coil I4, mounted on the magnetic core of thereactor, provides the necessary regulating means.

In accordance with my invention, coil I4 is energized with a directcurrent signal which is proportional to the signal in conductors 3 and4. A rectifying circuit, such as the bridge type rectifier I5, isemployed to change the alternating current signal from supply conductors3 and 4 to a pulsating direct current signal. Thus, the input terminalsI5a and I512 of rectifier I5 are connected respectively to conductors 3and 4 through the direct current blocking condensers I6 and I1, and theoutput terminals I50 and I5d of the rectifier are connected to aconventional direct current amplifier IS. The output of amplifier I8 isapplied to coil I4 of the reactor.

In the no-signal condition, when stylus 8 is stationary, the reactanceof winding I2 is such that the current flow in loop I heats stylus 8sufficiently that it produces a distinct substantially straight line onthe heat sensitive record sheet 9 as the record sheet moves at aconstant rate under the stylus. However, the heat produced by thiscurrent is insumcient for stylus 8 to make a distinct line when thestylus itself is moving.

In order to obtain the correct current upon movement of the stylus, bymy invention any signal applied to coil 2 to cause movement ordeflection of stylus 8 is also applied to amplifier [8 through rectifier[5. This, then, results in a substantial current flow in winding 14,since that winding is connected to be supplied from amplifier [8. Thecurrent in winding l4 increases the magnetic flux in the reactor coreand thereby reduces the reactance of winding l2. The reduction in thereactance of winding l2, of course, results in an increased current inloop I. This raises the temperature of stylus 8 and enables it toproduce a distinct line on record sheet H r in spite of the increasedspeed of the stylus during deflection. Thus by controlling the heatingof the stylus through the same signal which actuates the stylus, adistinct line is obtained on the recording sheet no matter what is thespeed of movement of the stylus.

When the actuating signal decays to the original no-signal condition,stylus 8 comes to rest and the current in winding l4 returns to itsoriginal small or zero value. This increases the reactance of winding l2and causes the current in loop I to decrease to the aforementioneddesired value for the no-signal position of the stylus.

The energy control system of this invention is, however, not restrictedto recording devices using a heat sensitive paper and a heated stylus.It may be employed with various other types of recorders. For example,in recording devices using an electrically sensitive recorder sheetwhich is marked by the passage of an electric current therethrough, theoutput of the amplifier would be applied directly across the recordersheet between the pen stylus and a stationary printing bar or plate.This eliminates the need for the reactor and its associated circuit insuch a recorder, and still provides an energy supply, i. e., markingcurrent, proportional to the speed of movement of the pen stylus.

While the present invention has been described r by reference to aparticular embodiment thereof, it will be understood that this is by wayof illustration of the principles involved, and that those skilled inthe art may make many modifications in the arrangement and mode ofoperation. Therefore, I contemplate by the appended claims to cover anysuch modifications as fall within the true spirit and scope of yinvention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In an inkless recorder having a recording range for recordingvariations in an electrical quantity on a record sheet having an energysensitive recording surface, a marking member disposed adjacent saidrecording surface and movable in response to variations of saidelectrical quantity, means connected to the source of electricalquantity to be recorded for deriving a control signal that variesthroughout said recording range in accordance with said variations ofsaid electrical quantity, and electrical connections for supplyingenergy to said recording surface through said marking member inaccordance with the control signal to effect an energy supply to saidrecording surface respon- 4 sive to said variations of said electricalquantity throughout said recording range.

2. In an inkless recorder for recording variations in an electricalquantity on a record sheet having an energy sensitive recording surface,a marking member disposed adjacent said recording surface and movable inresponse to variations of said electrical quantity, an inductive reactorhaving a magnetic core and a pair of windings, an electrical circuit forsupplying energy to said recording surface through said marking memberincluding in serial relationship a source of alternating current and oneof said windings, and an electrical circuit for energizing the other ofsaid windings in accordance with said variations in said electricalquantity, the interaction between said windings to cause said energysupplied to said recording surface to vary in response to saidvariations of said electrical quantity.

3. In an inkless recorder for recording variations in an electricalquantity on a record sheet having an energy sensitive recording surface,a marking member disposed adjacent said recording surface, a markingmember disposed adjacent said recording surface and movable in responseto variations of said electrical quantity, an inductive reactor having amagnetic core and a pair of windings, an electrical circuit forsupplying energy to said recording surface through said marking memberincluding in serial relationship a source of alternating current and oneof said windings, and an electrical circuit for energizing the other ofsaid windings including a rectifier connected to be energized inaccordance with :said variations of said electrical quantity and anamplifier connected to amplify the output of said rectifier and tosupply the amplified output to said other winding, the interactionbetween said windings to cause said energy applied to said recordingsurface to vary in response to said variations of said electricalquantity.

4. In an inkless recorder for recording variations in an electricalquantity on a record sheet having a heat sensitive recording surface, astylus disposed in contact with said recording surface and movable inresponse to variations of said electrical quantity, an inductor reactorhaving a magnetic core and a pair of windings, an electrical circuit forheating said stylus including in serial relationship a source ofalternating current, one of said windings and a stylus heating loop, andan electrical circuit for energizing the other of said windingsincluding a rectifier connected to be energized in accordance with saidvariations of said electrical quantity and an amplifier connected toamplify the output of said rectifier and to supply the amplified outputto said other winding, the interaction between said windings to causethe cur rent supplied to said heating loop to vary in response to saidvariations of said electrical quantity.

GEORGE F. GARDNER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,415,528 Craighead May 9, 1922 2,443,647 Waterman June 22,1948 2,454,966 Faus Nov. 30, 1948 2,457,131 Curtis Dec. 28, 19482,543,779 Hester et a1 Mar. 6, 195l

